Apparatus for reading



July 28, 1959 D. H.'sHEPARD 2,897,481

' APPARATUS FOR READING Filed Dec. 17, 1953 4 sheets-sheet 1 1W-f. 23 f4 E Z0 y ma@ fm2/WM www Mxima@ ATTORNEYS July 28, 1959 D. H. SHEPARD APPARATUS FOR READING 4 Sheets-Sheet 2 Filed Dec. 17, 1953 I NVEN TOR MMLMWM BEIM ATTORNEYS July 28, 19.59 D. H. SHI-:PARO 2,897,481

,f l APPARATUS FOR READING l l Filed Dec. 17, 1955 `4 sheets-'sheet 3 Pow l b Ra Y 17g; Il.

l l L g5 L ll l I l m 75 zur TIIEN- UFF P0155 ATTORNEYS July 28, 1959 Filed Dec. 17, 1953 D. H. sHEPAR-n 2,897,481

APPARATUS FOR READING 4 Sheets-Sheet 4 ffy/.

72 Tum-*OFF Pu/.sE INVENTOR Wggmmgw ATTORNEYS United States Patent O APPARATUS FOR IREADING David H. Shepard, Falls Church, Va., assignor to Intelligent Machines Research Corporation, Arlington, Va., a corporation of Maryland Application December 17, 1953, Serial No. 399,227

19 Claims. (Cl. 340-449) The present invention relates in general to methods and apparatus for interpreting intelligence and activating selected ones of a variety of output devices in accordance with decisions made on the basis of information sensed from the intelligence, and more particularly to devices having one or more input sensing units which scan items of information, recognize the items of information on the basis of selected unique qualities thereof, and operate output apparatus in accordance with the item of information recognized.

Briefly, the present invention relates to interpreter apparatus of the type arranged for scanning signals or items of information such as printed characters, Morse Code characters, and other intelligence-bearing items with respect to a variable time base, detecting the presence or absence of unique configurations of the intelligence-bearing signals, interpreting the presence or absence of unique configuration signals to recognize the signal or item of information, and presenting the recognition decision to an output device to record or reproduce the signal recognized. The invention has application particularly to the production of machines which will accept signals from an input device which is scanning a printed page such as a typewritten page and producing signals in accordance with unique features of the characters being scanned and ignoring unimportant features, interpret the signals to determine the unique identity of each character being scanned by the input device, and produce coded signals representing the character identilied to an output device such as a card punching device, a tape punching device, an electronic computer, or any other output unit which may be operated from coded information.

An object of the present invention is the provision of novel apparatus for interpreting signals produced in accordance with selected portions only of intelligence-bearing characters as unique configurations, recognizing the unique configurations, and reproducing the intelligencebearing items, which is adaptable to interpret a wide variety of configurations with accuracy on the basis of selected portions only of the configuration.

Another object of the present invention is the provision of improved reading apparatus for sensing and interpreting information-bearing characters which avoids the limitation on speed and accuracy of reading and interpreting incident to mechanical scanning means which scans portions only of the characters to recognize the same through detection of unique characteristics thereof, without the use of mechanical scanning components.

Another object of the present invention is the provision of improved reading apparatus for sensing and interpreting information-bearing characters which avoids the limitation on speed and accuracy of reading and interpreting incident to storage of shapes to be recognized on a mechanical scanning disk through the use of separate programmed electronic storage units which store equivalent information.

70 ner in which comparator circuits of the decision unit and 2,897,481 Patented July 28, 1959 Another object of the present invention is the provision of improved reading apparatus for distinguishing intelligence-bearing characters from unique characteristics of portions thereof and reproducing the same, which is adapted to be selectively programmed to recognize a wide variety of intelligence-bearing items. i

Another object of the present invention is the provision of apparatus for reading and interpreting intelligencebearing characters, in which means are provided to automatically position the area scanned by the device in accordance with the extent and location of the characters to be read.

Another object of the present invention is the provision of interpreting apparatus for use with an input device which scans items of information and produces electricalV signals in accordance with unique characteristics of portions of the items, which is capable of recognizing the item of information even though it may be disligured, incomplete, or incorrectly aligned with respect to the input scanning device.

Another object of the present invention is the provision of apparatus for interpreting items of information from electrical signals produced in accordance with unique characteristics of the items by an input scanning device, in which the interpreting apparatus is adapted to be readily programmed to sense and recognize different sets of facts pertaining to the viewed configurations, which facts relate the various segments of a character to each other rather than to the scanning base and thus do not depend on alignment.

Other objects, advantages and capabilities of the present invention will become apparent from the following detail description, taken in conjunction with the accompanying drawing, showing only a preferred embodiment of lthe invention.

In the drawing: Y r u Figure l is a schematic illustration of the mechanical components and a block diagram of the electrical circuits employed in my invention; n

Figure 2 is an illustration of the scanning pattern traced out by the electron beam in scanning visible items of information in accordance with the present invention, together with the points along the scanning path at which the electron beam is gated to produce spots of light;

Figure 3 is a block diagram indicating the circuit arrangement of the recognition pulse counter employed in connection with the present invention;

Figure 4 is a schematic diagram of a comparator or and circuit employed in the decision unit of the present invention;

Figure 5 is a schematic diagram of one of the thyratron primer circuits employed in the Temporary Memory unit of the present invention; Y

Figure 6 is a schematic diagram of one of the thyrat'ron shape memory circuits employed in the Temporary Memory unit;

VFigure 7 is a block diagram of 'the pulse shift register in the Temporary Memory unit;

Figure 8 is a schematic illustration of output storage v unit showing the routing of the thyratron-controlled relays to produce an output signal appropriate to the numerical character recognized; Figure 9 is a block diagram of a circuit that may be employed to produce end-of-character pulses;

Figure 10 is a program chart showing the circuit conl nections to be established in the Permanent Memory plugboard of the present invention to program the apparatus to recognize numerals from zero to nine;

Figure 1l is a schematic diagram illustrating the manthyratron circuits of the Temporary Memory unit are intercoupled in accordance with one phase of a program; and

Figure 12 is an illustration of a shape detection pattern ofone of the shape memory stages of the Temporary Memory unit shown with a group of numbers of an exemplary font of typekwhich the pattern is designed to distinguish.

The following detailed description, had with reference to the accompanying drawing, wherein like reference characters designate corresponding parts throughout the several figures, is of a preferred embodiment of the invention only, wherein the apparatus is programmed to scan, detect, interpret and reproduce numerical characters from zero to nine read from typewritten characters on a sheet of paper bearing such numbers. It is to be understood, however, that the apparatus in practice is programmed to read all alphabetical characters, numbers from zero to nine, and a number of preselected punctuation marks, or other characters such as arbitrary characters designed to instruct the apparatus to perform certain functions, the following description being confined to a program for reading numbers from zero to nine merely for the purpose of simplifying the description and facilitating a clear understanding of the invention.

The device is particularly designed to read typewritten characters on a sheet of paper starting at the upper lefthand corner of the page and identifying each character in turn, reading from left to right through each succeeding line, and to automatically edit the typewritten sheet and advance the same through recognition of certain characters especially assigned to these functions.

Referring particularly to Figures 1 and 2 of the drawing, a sheet of paper bearing characters to be read by the apparatus which, for the purpose of this description will be typewritten numbers from zero to nine, is to be fed through the field of view of a light sensitive device 21 such as a multiplier photoelectric cell. The photoelectric cell 21 is designed to receive light imaged upon the sheet 20 by a suitable optical system 22 and yemanating from the screen 23 of a cathode ray tube 24. The light from the screen 23 of the cathode ray tube 24 which is imaged on the character-bearing sheet 20 is reflected from the 'l 2,897,481V l surface of the sheet 20 through a suitable shield 25 disf posed between the sheet 20 and the photoelectric cell 21 except when light focused by the optical system 22 on the sheet 20 falls upon a portion of a printed character, the shield 25 being provided to shield the light sensitive element of the photoelectric cell 21 from spurious light rays. y The cathode ray tube 24 employed in the scanning unit of the present invention is of the conventional type supplied with pairs of vertical and horizontal electrostatic deflection plates 26 and 27, respectively, and an intensity control grid 28 for gating the electron beam produced by the electron gun of the cathode ray tube 24.' Saw tooth voltage wave forms are supplied to the pair of vertical and horizontal deflection plates 26 and 27 from conventional vertical and horizontal sweep generator circuits 29 and 30 in preselected time relation to produce a plurality of horizontal scanning lines resembling the scanning routine used in commercial television, `resulting in the scanning pattern illustrated in Figure 2.

' The vertical and horizontal sweep generator circuits 29 and 30 are each triggered through leads 31 and 32, respectively, plugged to sockets in a programming plugboard for establishing the circuit conditions of the particular program of the unit, indicated at 33 in the drawing and entitled Permanent Memory. The leads 31 and 32 plugged to sockets in the plugboard 33 are conductively jumped to sockets to which scale of 32 and scale of 2 pluses, respectively, are fed from appropriate leads 34b and 34C extending from a clock pulse counter unit 34, which will be later described in greater detail.y In general, the clock pulse counter 34 consists of a number of cascaded tlip-op circuits producing pulses at preselected binary multiples of a continuous stream of pulses produced at a preselected constant pulse reptition frequency by a clock pulse generator 35. This preferably consists of multivibrator circuits arranged to generate a chain of well shaped pulses at a frequency of 25 kilocycles per second, which are supplied to a socket on the plugboard 33 through a lead 35a, to which the input lead 34a of the counter unit 34 is jumped at the plugboard 33.

As this description progresses, it will be noted that all electrical connections having relation to timing or discriminating functions in the device are brought through the Permanent Memory which in this embodiment takes the form o f the plugboard 33, thus providing a readily available facility whereby the circuits can be conveniently changed to program the device for a wide variety of conditions.

It will be seen that as the horizontal and vertical sweep generators 30 and 29 are triggered by every second pulse and every thirty-second pulse, respectively, produced by the clock pulse counter unit 34, the electron beam produced in the cathode ray tube 24 will be swept over its phosphor-coated screen 23 in a series of parallel horizontal lines progressing from the top to the bottom of the screen, as illustrated by the dotted lines on Figure 2. This triggering of the horizontal and vertical sweep generators 30 and 29 preferably occurs 180 out of phase with occurrence of the pulses at the output of the pulse generator 35, which phase shift may be introduced in the input of the sweep generators in any suitable manner, for example, by a single-shot multivibrator. The exact number of horizontal lines to be swept across the cathode ray tube screen 23 may vary from program to program, but for the purposes of the preferred embodiment herein described, sixteen horizontal scanning lines have been ernployed.

To produce a scanning raster on the screen of the cathode ray tube 24 with reference to which selected spaced points on the `character area of the screen 20 may be analyzed, the intensity grid 23 of the cathode ray tube 24 in one preferred embodiment of the invention is normally biased below cut-off, and is intercoupled through lead 28a to a terminal on the Permanent Memory plugboard 33 which is bridged to a lead 35a carrying each pulsey generated by the clock pulse generator 35 at the pulse repetition frequency of the generator 35. The pulses on the leads 31 and 32 triggering the vertical and horizontal sweep generators 29 and 3i), however, are delayed in phase relative to the pulses coupled through the lead 28a to the cathode ray tube grid 28, in the manner previously referred to, so as to produce a pair of horizontally spaced groups a and b of vertically aligned spots of light 1a to 16a and 1b to 16]), spaced symmetrically relative to the vertical medial axis of the cathode ray tube screen 23.

These vertically aligned groups a and b of spots constitute the scanning raster for the apparatus, with reference to which selected points along each character on the sheet 20 are analyzed to permit identification of the character. The image of the cathode ray tube raster thus produced is projected through-the optical system 22 onto the character-bearing area of the paper 20 to be read, and is adjusted to such a size that the vertical height of the scanning raster is greater than the tallest character to be scanned and the width of the raster is approximately equal to half of the Width of the Vaverage character to be scanned. -In a preferred embodiment the raster is adjusted in -size so that the height of the digits or characters occurring on the printed Vsheet coversl ten to twelve linesalong the scanning raster. This provides a limited degree of vertical adjustment for misalignment of characters. In another embodiment, a scanning raster of twenty to twenty-four lines has been used for characters covering'ten to twelve lines to give greater adjustment.

f Whenever an uninked portion of the sheet 20 is traversed by the scanning beam at a point in time corresponding to the projected image of a spot on the scanning raster, a substantial portion of the light impinging upon the sheet will be retlected to the photocell 21 causing a pulse of increased current and resulting in -a negative .going voltage pulse of substantial amplitude in the photocell output. Whenever an inked portion of a character on the sheet 20 is similarly traversed by a scanning spot, a much smaller portion of the impinging light will be reflected to photocell 21 and the result-ing negative going photocell output voltage pulse will be of greatly reduced amplitude. Those portions of the sheet 20 which are traversed by the scanning beam, but which do not correspond in time to spots `on Ithe scanning raster, have no effect on the photocell output since during these times, nogl-ight will be emitted, and no light retlected. Only thev dark current will flow in the photocell 21 and its output lead will be substantially rat the positive supply potential. Thus :the output of photocell 21 will be characterized by a high positive potential on which are entrained negative pulses of relatively large amplitude resulting from scanning the uninked portions of the sheet 20 and negative pulses of greatly reduced amplitude resulting from scanning inked portions. These photocell output pulses are coupled to an amplifier 36 which amlities 'the intensity of the pulse to a usable value, and which preferably is controlled by conventional automatic gain control means responsive to the intensity of the incoming signal over a period of time to automatically increase the gainl of the amplifier 36 as the input signal weakens. n Coupled to the output of the amplifier 36 is a quantizer or voltage disc'riminator 37, which may be a conventional ampliiier stage having a preselected bias on the input grid rpermitting the tube of that stage to conduct and produce an output signal only when the voltage of the pulse coupled thereto from the amplier 36 is above a critical threshold voltage which is arbitrarily set to correspond to a desired darkness or contrast level anticipa'ted in 'the reading problem. The quantizer 37 therefore produces a constant voltage output pulse when a valid `hit or inked area is detected by the photocell 21.

The quantizer 37 therefore produces a constant positive voltage output both during the intervals between scanning spots and during those scanning spots when a valid hit or inked area is detected by the photocell 21. Negative pulses will be entrained in the output of quantizer 37 when either the uninked portions of sheet 20 or inked portions of less than the desired darkness or contraSt level 'are intercepted by the scanning raster spots.

Means are provided for producing a positive output pulse whenever an inked character portion is detected for one of the spots of the scanning raster. To this end, the train of clock pulses produced by the clock pulse generator 35 is 'coupled from the plug board 33 to one input of a gating circuit 38 through lead 38a and the output of quantizer 37 is applied to the other input of the' gating circuit 38. The gating circuit 38 is preferably a multi-grid vacuum tube having the clock pulse on one gnid and the quantizer negative output pulses on the other grid, the tube being biased to conduct only when thequantizer output is positive simultaneously with the arrival at the gating circuit 38 of a clock pulse. The output pulse of gating circuit 38 constitutes a recognition pulse designated R0 in the embodiment described above land is analyzed in connection with certain other recognition pulses and a known time base to identify the'character or number being read.

Means are also provided for producing an output pulse when no inked character pontion is 4detected for one of the spots on the scanning raster'. A conventional inverter 39 serves to reverse the polarityI of the output signais of quantizer 37 which are coupled to its input. The negative pulses of quantizer 37 corresponding to detection of uninked or portions of less than desired darkness 6 for spots of the scanning raster will cause positive pulses in the output of inverter 39. At all other times when the output of quantizer 37 is positive, inverter 39 will be caused to have a negative output potential. The positive output pulse of inverter 39 is termed a non-recognition pulse and is designated 1%.

A cascade of binary counters stepped by the clock pulses produced by the clock pulse generator 35 might be employed as the sole counter unit inv this system, producing pulses on separate output leads as the count advances through each scanning cycle in accordance with occurrence of the spots in the scanning raster to provide a pulse time base by which the particular spot of the scanning raster from which the hit occurred could be identified, Such an arrangement, however, introduces serious alignment problems into the identification of characters as accurate interpretation could be achieved only when the characters are precisely aligned in a particular relation to the scanning raster.

In order to avoid this alignment problem, a recognition pulse counter 40 is provided which counts recognition pulses produced at the output of gating circuit 38 arising from only one vertical group of spots on the scanning raster: for example, only recognition occurring in the group of Spots 1a to 16a. The components making up such a recognition pulse counter are illustrated in Figure 3.

The input stage of the recognition pulse counter 40 comprises an and circuit 41, of the type which is commonly known and used in electronics computer design, which is sensitive to the polarity and time relation of two or more input signals to produce an output signal when all input signals occur simultaneously. An and circuit which is satisfactoryfor this input stage 41 may consist of a pair of germanium diodes formed of 1N34 crystals arranged in parallel with the plates coupled through a resistor to a preselected positive voltage source and the cathodes coupled directly to separate sockets in the plug board 33. Every second pulse produced by the clock pulse counter 34 and `synchronized with the spots 1a to 16a of the scanning raster, obtained for example from the lead 34b, is coupled to one of the cathode leads 41a of the and circuit 41, and the recognition pulse at the output of the gating circuit 38 is coupled to the other cathode lead 4117.

When the tirst recognition pulse and one of the pulses synchronized With the spots 1a to 16a arrive simultaneously at the and circuit 41, a maximum voltage output pulse occurs on the output lead 41C of the and circuit, since no diode is holding the voltage down. This output pulse is amplied by a conventional amplifier 42 and coupled to the input of a conventional flip-flop circuit 43, triggering the flip-Hop circuit. The pulse produced in the flip-flop circuit on the occurrence of the maximum voltage pulse at the output of the and circuit 41 is coupled through the lead 43a to the clipped ampliiier 44, which clips the pulses at plus 25 volts and minus 25 volts. The clipped pulses are then supplied through output lead 44a to a socket of the plugboard 33 to be available for use in other parts of the system.

The ip-op, in accordance with conventional pract-ice, comprises a pair of triodes connected as a balanced trigger circuit, wherein either triode may be conducting current while the other is cut oli. When a preselected pulse of voltage is applied 4to the circuit, the conditions of conductionnon-conduction are reversed and remain so until the application of another like pulse at the same input point. v

The recognition pulse counter comprises four identical stages of flip-flop circuits 43, 45, 47 and 49. Each stage is coupled to the input point of the next succeeding stage so that two reversals in any given stage will result in a single reversal in the next succeeding stage. Thus the scale of 2" pulses produced at one plate of the nip-nop stage 43 are coupledV through output lead 4313i to the second flip-op stage 45. The scale of 4 output pulses at one plate of the nip-flop stage 45 are coupled through output lead 45a, a clipped amplier 46 identical with the clipped amplifier 44, and output lead '46a to another socket o-f the plug board 33. Similarly, the scale of 4 pulses at the other plate of the flip-flop stage 45 are coupled through lead 45h to a third flipop stage 47, the scale of 8 pulses on one plate being coupled through lead 47a, clipped amplifier 48 and output lead 48a to another socket of the plug board 33, and the scale of 8 pulses produced at the other plate of the flip-hop stage 47 are coupled through lead 47b to a fourth flip-flop stage 49, scale of 16 pulses produced thereby being coupled through output lead 49a, clipped amplifier 50 and output lead 50a to another socket of the plug board 33.

p Additionally, a reset circuit is associated with each of the llip-op stages 43, 45, 47 and 49, to terminate the count and reset the Hip-flop stages to zero the rst time that no recognition pulse is received in the group of raster spots 1a to 16a. This reset circuit comprises an and circuit 51 identical with the and circuit 41, having input leads 51a and 51b respectively coupled to separate sockets of the plug board 33, the lead 51a receiving pulses synchronized with each one of the spots 1a to 16a, indicated by the letter a and lead Slb receiving a non-recognition pulse denoted Rw produced by the inverter 39 when no recognition pulse is received at the time of sampling. The positive output pulse produced by the and circuit 51 on simultaneous occurrence of these two pulses is fed through lead Sllc to an amplier 52, where the pulse is amplified to an appropriate value and coupled through lead 53 to each of the ilipllop stages 43, 45, 47 and 49 to reset the flip-flop stages to zero.

The recognition counter circuit therefore produces an output Voltage at the plug board socket connected to lead 44a which changes polarity at every consecutive recognition pulse occurring in coincidence with one of the vertical group of spots 1a to 16a, `an output voltage at the plug board socket connected to lead 46a which changes polarity `at every second consecutive recognition pulse occurring in `sequence in coincidence with the raster yspots 1a to 16a, -a voltage at the plug board socket connected to lead 48a which changes polarity at every fourth `consecutive recognition pulse occurring in sequence in coincidence with the raster spots 1a to 16a, and a voltage at the plug board socket connected to lead 50a which changes polarity at every eighth consecutive recognition pulse occurring in sequence in coincidence with the raster spots 1a to 16a. The voltages coupled yto the plug board sockets from the amplifiers 44, 46, 48 and 50 `are detected by conventional circuitry to establish the counts of successive R pulses in accordance with the binary number system. All these voltages, when reset, return to la negative potential.

Voltages occurring on the plates of each of the flipflop stages 43, 45, 47 and 49 which are opposite the voltages brought to the plug board 33 through leads 43a, 45a, 47a and 49a may also be brought directly to the plug board 33 for use in other parts of the system. From the apparatus above described, it will be seen that the electron beam of the cathode ray tube 24 is scanned by voltage applied to the electrostatic deflection plates 26 and 27 and gated by the voltage on the intensity grid 28 to produce the vertical group of spots of light 1a to 16a and the laterally spaced vertical group Yof spots of light 1b to 16b on the phosphor screen of the cathode ray tube. These spots will be imaged on the character area of the sheet 20 by the optical system 22. When the projected image of any of the spots of light 1a to 16a, 11b to 16b, strikes a portion of a character on the sheet 20, which will be dark and therefore of lower reflectivity than the sheet 20, the reduced intensity of the light rellected tothe photocell 21 produces an output voltage which is amplified by the amplifier 36 and fed to the quantizer 37 which enables the gating circuit 38 to produce an output pulse termed a recognition pulse when the voltage is greater than a preselected critical threshold voltage which is arbitrarily set to correspond to a desired darkness or contrast level. Therefore, for each spot 1a to 16a and 1b to 16b which encounters a. portion of the intelligence-bearing characters on the sheet 29, a recognition pulse R0 is provided at the outpu-t of the gating circuit 38 which is fed to the recognition pulse counter 40 by which successive recognition pulses R0 are counted and outputs produced appropriate to the count. The recognition pulses R0 at the output of the gating circuit 38 are also illustrated in Figure 1 as coupled directly to comparator circuits 56 of the decision unit 55, although for convenience these may be coupled through the plug board 33 to facilitate rewiring of the system in accordance with different programs. Also, whenever any of the spots 1a to 16a and 1b to 16b fail to strike a portion of a character on the sheet 20 so that no output pulse is produced by the photocell 21, a non-recognition R0 is provided at the output of the inverter 39 in the manner previously described and is fed to the plug board 33. In this manner, recognition pulses R0, non-recognition pulses lig,- and recognition pulse counter output pulses indicative of the number of successive recognition pulses counted are available to be analyzed by various comparator or and circuits 56 of the decision unit 55 as to the sequence and recurrence of the recognition and non-recognition signals and the relative time spacing of the same to facilitate interpretation of the signals and detection of the identity of the character.

A decision unit, indicated by the reference character 55, is provided in the apparatus to analyze the recogni-. tion and non-recognition pulses produced by the quantizer 37 and gating circuit 38, respectively, in conjunction with selected ones of the pulses produced on the output leads 44a, 46a, 48a and 50a of the recognition pulse counter 40 to determine which of certain conditions predicted in the program established for the apparatus exist with respect to a given character and produce an appropriate output signal.

The decision unit consists of a large number of identical comparator or and circuits, indicated by reference character 56, a schematic diagram of one of which is illustrated in Figure 4. Each of the comparator circuits 56 preferably consists of four germanium diodes 57, 58, 59 and 60, which may be 1N38 diode crystals available on the commercial market, 4the plate of each of which is connected through leads 57a to 60a, a common buss 61, and resistor 62 to a positive 75 volt source, The cathodes of each of the germanium diodes 57 to'60 are coupled through leads 57ib to 60b to separate lsockets of the plug board 33. An yadditional lead 63 extends from the common buss 61 to which each of the anodes are connected to a fifth socket of `the plug board 33. It will be rapparent therefore that leads extending from the output of 'the stages producing the recognition and nonrecognition pulses or from the outputs of priming thyratron stages, to be later described, and leads extending from various other points in the system such as selected ones of the output pulses of the 4recognition pulse counter' 40, may be coupled to selected ones of the sockets connected to the cathode leads 57b to 60b of any one of the comparator circuits 56. lf the several pulses are of the same positive polarity Iand occur simultaneously, `all the pulses being assumed to be of equal voltage, the reduced IR drop through the common resistor 62 will produce a positive voltage pulse at the socket connected to the output lead 63.

In order to temporarily store information provided by the other units of the system, particularly the comparator circuits 56, as when a ycomparator circuit has produced lan output on simultaneous reception of a 'recog nition pulse and a specific counter output pulse, the pres ent vsystem is provided with la group of circuits forming what will be termed `a temporary memory, indicated by reference character 65. The functions of this temporary memory unit 65 are to store up in binary coded form Ainformation presented in the form of output pulses from other units and give up the information in the form of a positive or negative output Voltage or picking up or not picking up a relay -at a selected time in the operating cycle, and to change the information stored by erasing the previous information stored .and store new information presented by some unit of the system. One example of the type of information which the temporary memory unit can store is a binary indication `of which specific shapes or strokes which may be looked for to identify a character have occurred since the beginning of the :scan of a particular character being read. Another example is the sequence of occurrence of such strokes.

The storage medium employed in the temporary memory may be vacuum tubes, a magnetic drum, magnetic binaries, a cathode ray tube, delay lines, relays, or like storage means known in the electronic computer arts. In the preferred embodiment herein disclosed, however, the temporary memory 65 is made up: of a plurality of thyratrons triggered by the decision unit 55. The thyra tron circuits of the temporary memory unit 65 are preferably of two types, designated priming stages 66 and shape memory stages 67. In a preferred embodiment, twenty identical priming stages 66 and twenty identical shape memory stages 67 are provided to be coupled through the plug board 33 with selected ones of the comparator circuits 56 and other units of the system in accordance with the program of the system.

The preferred form of the priming thyratron stages 66 is illustrated in schematic form in Figure 5, wherein the thyratron tube is designated by reference character 68. The control grid 68a of the thyratron 68 is intercoupled with a socket of the plug board 33 through a resistor 69, the plate 68b is coupled directly to a positive 100 volt supply, and the cathode 68C is coupled to a negative 50 volt supply through resistors 70a and 70b, a lead 70C being tapped off at a point between the cathode resistors'70a and 70h and extending to a socket of the plug board 33 to present the thy-ratron output at this socket. Additionally, a diode 71 is coupled between the cathode 68e above the resistor 70a and ground with the cathode of the diode connected to the cathode 68C to insure that the thyratron cathode 68e does not go below ground potential. A turn-off pulse input lead 72 is also coupled to the same point on the cathode 68C, the lead 72 having a capacitor 73 and resistor 74 in series. The pulses to be supplied through the lead 72 to turn off thel priming stages are preferably the end-of-frame pulses Tp occurring at the end of each complete scanning raster or the end-of-character pulses Tc and are of such magnitude and polarity as to elevate the cathode 68e to cutoff condition and terminate conduction through the thyra-V tron 68. The turn off pulses may be derived from a number of sources in the system, but in a preferred embodiment, the end-of-frame turn off pulse, TF, is produced by a thyratron triggered by the pulse which returns the scanning beam to start scanning a new raster, and the end-of-character turn off pulse, TC, is` produced by the source indicated in Fig. 8 actuated in 'a manner to be later described.

The preferred form of the shape memory stages 67 is as illustrated in Figure 6. The control grid 75a of the thyratron 75 is brought to a socket of the plug board 33 through a resistor 76, the cathode 75C is coupled directly to ground, and the plate 75b is coupled directly to a terminal 77 which in turn is coupled to one terminal of one of the relays 86-93 having another terminal connected to a positive 100 volt source through normally closed contacts of an end-of-character reset relay 95.

In the programming of the system, as will later appear, the thyratron priming stages 66 and other appropriate plug board voltage sources will be intercoupled with the shape memory stages 67 through comparator circuits 56 in the same manner used .for tiring the priming stages themselves, tiring a shape memory tube when the appropriate conditions are present. In this manner, for example, a pair of thyratrons may be made sensitive to the lsequence of detection of events by the comparator circuits 56, and the shape memory stage, by tiring, will record the fact that the proper sequence has occurred.

An additional component of the temporary memory unit 65 is the pulse shift register 80, illustrated .in Figure 7. This unit constitutes a source of recognition pulses delayed by intervals equal to the time spacing of successive spots of the scanning raster, or `multiples thereof, to be presented to comparator circuits 56 with selected later recognition pulses to determine coincidence of certain conditions. The pulse shift register as shown -in Figure 7, employs an amplifier I81 as the input stage, the input of the amplifier 81 being coupled to a socket of the plug board 33. Associated with the emplifier 81 are a plurality of identical one-pulse delay stages 82, equal to the number of delay intervals desired for the program of the system, which stages may be formed of a delay line, sequenced trigger circuits, or like known fixed delay means. These delay stages 82 are arranged in succession with their inputs coupled to the preceding stage; One output is coupled to the succeeding stage, and another output is coupled through clipped amplifiers 83 for limiting the magnitude of the output pulses to a standard value, preferably x25 volts, and is applied "to separate sockets of the plug board 33. These delayed output pulses are designated Rai, where i is the number of delay intervals.

The output leads 77 from the plates of each of the shape memory stages 67 extend to separate relay coils of a bank lof relays constituting an output storage unit 85, illustrated schematically in Figure 8. This output storage unit 85 is similar to the routing relay network making up the interpreter circuit 50 of my co-pendi'ng application S.N. 213,338, now Patent No. 2,663,758, issued December 22, 1953, and illustrated in Figure 8 of that application. Specifically, the output storage unit 85 in the preferred embodiment herein described consists of eight routing relay coils 86-93, bearing Roman numerals LVIII respectively. The routing relay coils 86-93 are associated with relay contact arms 8611-93a respectively, to be operated in various combinations in accordance with tiring of shape memory stages 67 to establish a current routing to a particular output terminal to be connected to appropriate input terminals of an output device such as particular keys of a solenoid operated electric typewriter. The lower terminal of each of these relay coils 86-93 are connected through a cornmon lead 94 and the normally closed contact arm 95a of an end-of-character reset relay 95 to the positive terminal of a relay power supply. The other terminal of fthe coil of relay 95 is supplied with a delayed end-of# character pulse from a source to be later described.

The upper terminals of the relay coils 86-93 are coupled to the output leads 77 of selected shape memory stages 67. With this arrangement, firing of the thyratron of a particular shape memory stage 67 while the character is being scanned will energize the relay coil of the group 86-93 coupled thereto shifting its contact arm to close the output device actuating voltage routing circuitV through that relay. No voltage is applied to the routing circuit through the contact of these relays however until l an end-ofcharacter pulse is produced signifying detection of the end of the character being scanned, as will be later described.

The combinations of the relay coils 86-93 to be energized to establish the routing for presenting signals l i1 at terminals 96-105 for the numerals 0-9 respectively in theprogram illustrated in Figure is as follows:

O-coils 88 and 93 energized l-coil 89 energized, but 86 and 88 not energized 2-coil 87 energized, but 88, 89 and 91 not energized 3-88 energized, and 93 and 92 not energized or 91 energized and 88, 89 and 92 not energized 4-coils 88 and 92 energized, but 90 and 93 not energized 5-no coils energized 6-coils 89 and 86 energized, but 88 and 90 not energized 7-coils 89, 86 and 90 energized, but 88 not energized 8-coils 91 and 92 energized, but 88 and 89 not energized 9-coils 88, 92 and 90 energized, but 93 not energized The output terminals 96-105 provide separate output signals identifying the character read by the terminal on which the signals occur. These output terminals may be coupled 'to any desired output device, but in the preferred embodiment herein described are connected to the key-actuating solenoids of an electric typewriter to actuate the keys in accordance with the character identihed and reproduce the same.

In the program chart of Figure l0, the reference characters P1 to P8 refer to thyratron priming stages of the type illustrated in Figure 5 of the drawing having an and circuit 56 coupled to the input thereof; the symbol PE designates a thyratron priming stage described in greater detail in connection with the circuit illustrated in Figure 9 for producing the end-of-character reset pulse; the symbols M1 to M8 designate shape memory stages of the type illustrated in Figure 6; the symbols a and b designate counter pulses produced by the clock pulse counter in synchronism with the spots of the series la to 16a and lb to l6b, respectively, of the scanning raster; the symbol d0 indicates the derivative of an output pulse; the numerals designate the outputs of the correspending binary counter stages of the recognition pulse counter 4G; the symbol Tc designates the endofchar acter pulse; the symbol TF designates the end-of-frarne pulse produced in synchronism with every 32nd pulse produced by the clock pulse counter 34; the symbolnTFD indicates a slightly delayed end-of-frame pulse; and the symbols R0 and lo designate the recognition and nonrecognition pulses. In that chart, the rst column 106 contains the symbols indicating the priming and shape memory stages, the next four columns 107 to 110 indicate the various input conditions necessary to fire those stages, the column 111 indicates reset or turn off pulses applied to that stage, and the column 112 contains an illustration of the shapes effecting firing of the stages.

The end-of-character reset pulse, hereinbefore referred to, is produced in the following manner, reference being had particularly to Figure 9 and the program chart illustrated in Figure l0. The immediate components of the circuit producing the end-of-character pulses comprise an and circuit 113 identical with the an circuit 56 illustrated in Figure 4, the output of which is coupled to the input of a thyratron priming stage 114, designated PE in Figure l0. The output of the thyratron priming stage 114 is coupled through a relay coil 115 to a -25 volt supply. A source of the output device actuating voltage is coupled through the normally open contacts 11561 of the relay coil 115 to the input terminal 116 (see Fig. 8) of the output storage unit 85 providing the source of the output voltage to the output terminals 96-105 for actuating the output device.

The output of the thyratron priming stage 114 is also coupled through a delay stage 117, which may be a single shot multivibrator designed to delay-the output of the priming stage 114 coupled therethrough for a period of time equal to that required to energize the output device. This delayed voltage is coupled from the delaystage 117 to energize a thyratron 118, the plate of which is coupled directly through the coil of relay '95. The terminal of the turn ott pulse lead 72 of eachof the thyratron priming stages 66 to be turned off by the TC pulse is coupled through the normally open second relay contact b of the relay 95 to a |l00volt supply. Each of the priming stages 66 which are in a state of conduction will then be cut off by the positive surge produced bythe relay contact 95b upon the delayed conduction of the thyratron 118 and consequently energization of the relay 95, the relay cutting itself off when it withdraws its contact 95a.

Reference to -the program of Figure l0 will indicate that the inputs coupled to the thyratron priming stage PE and its and circuit, identified as 114 and 113, respectively, in Figure 9, are the output of the priming stage P3, the end-of-frame pulse, and the inverse of the output of priming stage P7. Conduction in the priming stage P3, in turn, is effected only when the priming stages P1 and P2 are in a conducting state. The reason for depending triggering of the priming stage PE on these various factors is as follows. It will be noted that the number 4 appears opposite the symbol P1 in Figure 10. This means that in the program there indicated, the priming tube P1 will only be tired when the recognition pulse counter 40 has reached the count of 4, that is, that four successive spots of the series of spots la to 16a of the scanning raster have produced hits. This is accomplished by applying the pulse produced at the plate of the appropriate stage of the recognition pulse counter 40 which is indicative of a count of 4 successive hits on the "a side of the scanning raster to the input of the comparator circuit 56 coupled to the priming stage P1 to iire that priming stage. The purpose of the stage P1 is to eliminate consideration of stray specks on the paper as a character to be read, by requiring that any dark item must have at least one short vertical line segment to be considered a character.

The purpose of the second priming stage P2 is to insure that a dark area is also seen in coincidence with one of the second series of spots 1b to l6b before the dark area will be considered a character. To this end, each recognition pulse R0 at the output of the gating circuit 38 is coupled to one socket of the and circuit 56 coupled to the input of primer P2 and each clock pulse coincident with the modulating pulses on the cathode ray tube grid 28 producing the spots lb to 16b is coupled to another socket of that and circuit. Simultaneous arrival of a recognition pulse and a pulse signifying a spot of the series 1b to l6b will therefore trigger the primer stage P2 indicating occurrence of a dark area on the side b Of the scanning raster.

The priming stage P3, as indicated in the program, only res when both the priming stages P1 and P2 have red and the end-of-frame pulse TF reaches the input and circuit of the priming stage P3. When priming stage P3 tires, it is generally safe to assume that `the character to be read has now entered slits a and b of the scan :ning raster formed by spots la to 16a and lb to l6b, respectively.

The input and circuit of the priming stage P7 is coupled to clock pulses coincident with the cathode ray tube modulating pulses producing spots la to 16a and to the output of the gating circuit 38, so that the priming stage P7 is tired only when recognition pulses are received for at least one of the group of spots 1a to 16a. This stage P7 is reset at the end of each complete cycle by a delayed end-of-frame pulse TFD. The output lead 70C of the priming stage P7, which has a voltage of minus 25 volts when the thyratron has not been tired and plus 25 volts when it has been tired, is coupled through a conventional inverter stage which produces a corresponding voltage of opposite polarity relative to that on the lead 70C, and this inverted output, designated P7, is coupled to one of the input leads of the and circuit for the prlrnlng stage PE. Thus a positive voltage is applied to the mput circuit of PE from P7 upon arrival of an endat the end of scanning of a complete has not fired for one complete series of-frame pulse TF frame only when P6 of spots 1a to 16a.

From the above it will be apparent that 'the priming stage PE will be tired to initiate the end-of-character sequence when the priming stage P3 has been tired, indicat ing that no recognition pulse was produced for the spots 1a to 16a during one complete frame.

To facilitate a complete understanding of the operation of this system -to detect and recognize numerals, the operation of the decision unit and temporary memory in detecting three of the shapes used in actually distinguishing numerals will be described. All of the shapes used to detect and distinguish numerals `in the program indicated tin Figure l and the conditions necessary to fire the priming and shape memory stages to detect these shapes is indicated fully in the program chart.

The simplest shape used in this program is that appearin-g in connection with the shape memory stage M4. The number 8 is the only symbol following the symbol M4, indicating that the only condition necessary to re the shape memory stage M4 is that the fourth stage of the recognition pulse counter 40 has changed to the positive state signifying that the counter has reached a count of eight. The effect of this is to iire the memory stage M4 whenever recognition pulses R6 are produced for a succession of eight of the spots la to 16a of the scanning raster. Since the height of the characters in this program is assumed to be equal to approximately l0 to 12 horizontal scanning lines, the tube M4 will tire only for those characters having a reasonably long vertical line segment. The characters 1, 6 and 7, for example, in the font of type illustrated in Figure 12, have this characteristic, while a vertical line segment of such length does not occur in the numbers 2, 3, 5 and 8 in this font of type. Firing of the memory stage M4, which is intercoupled with the relay coil 89, (IV), will energize the relay coil 89 to attract its contact and route the output of relay 115 energized by the end-of-character priming tube PE on the terminal 116 to the leads of output `terminals 97, 102 or 103 which are coupled to the solenoids of the output device actuating the type for the numbers l, 6 and 7.

`A more complicated shape is that described for the memory stage M1. The purpose of this stage is to distinguish between the numeral 1, which does not contain the shape detected by this stage, and the numerals 6 and 7 which do contain lthis shape. The shape detected by the memory stage M1 is indicated by reference character 120 in Figure l2 and is superimposed over the numerals 1, 6 and 7 in that figure.

A schematic diagram of the priming stage P6 and the shape memory stage M1 interconnected in a manner to detect this shape is illustrated in Figure 11.

Referring to the program chart of Figure 10, the input voltages applied to the and circuit for the memory stage M1, as indicated in columns 107, 108 and 109, are designated Iby the symbols bj P6 and R6. The symbol b refers to input pulses synchronous with the spots lb to 16b on the left side of the scanning raster, and the symbol R6 designates the recognition pulses obtained from the output of the gating circuit 38. Simultaneous occurrence of the voltages b and R6 indicates that recognition has occurred in the series of spots on the left side of the scanning raster after some other event or condition is present as signified by the symbol P6. The condition P6, which -is physically represented by iiring of the priming stage P6, in turn is a combination of other events, as indicated by the symbols in the columns 107-110 beside the symbol P6, namely, P6, R6 and a.

Since the symbol P6 occurs beside the symbol P6 in the column 106, it is necessary to refer back to the program conditions for P6 to understand those for P6. Firing of the priming stage P6 is also the product of a combination of events indicated in columns 107-110 as l, 2` and P2. This requires further references back to the program conditions for P2. The symbol P2 indcates firing of the thyratron priming stage P2 on simultaneous occurrence of a recognition pulse R6 synchronized with one of the spots 1b to 16h, as has already been described in connection with the end-of-character sequence. The symbol P2, translated into simple terms, means recognition in the slit b of the scanning raster.

The symbols l, 2 and P2 beside the symbol P6 in column 106 indicate that the thyratron P6 will be fired upon occurrence of pulses from the recognition pulse counter 40 totalling a count of 3 successive recognition pulses on the a side of the scanning raster, together with firing of thyratron P2 which requires a recognition pulse R6 for a spot on the b side. Since the priming thyratron P2 must be conducting when the count of 3 recognition pulses is completed for the thyratron P6 to be fired, the thyratron P2 must have been red before the end of the 3-count vertical line segment. The P6 following the symbol P6 indicates therefore that the shape memory stage P6 has -been red by the occurrence of a vertical line segment on the a side of the scanning raster which is at least 3 counts long and a spot on the "b side above the bottom of the line segment.

The other symbols, appearing besides P6 are l-6 and "a. 'ft-6, as previously described, symbolizes a nonrecognition pulse which is produced at the output of the inverter 39, and a indicates pulses synchronized with the spots la to 16a of the scanning raster. The

effect of this pair of conditions R-o and a is to require that the vertical line segment of the character occurring in slit a of the scanning raster must come to an end before the priming tube P6 will tire.

The relative positions of the components of the shape effecting tiring of the memory stage M1 is pictured at 120 in Figure l2. The three dark spots 121, 122 and 123 at the right hand side of the group illustrate the occurrence of a vertical line segment at least three counts long required to iire the priming stage P6. The open spot 124 below the three dark spots 121 to 123 symbolizes the occurrence of a nonrecognition pulse ITO in the "a side of the scanning raster following the vertical line segment, this condition being detected by simultaneous occurrence of -an a pulse and a nonrecognition pulse o'.

The tiring of the priming stage P2 is a condition precedent to tiring of the stage P6, so that the occurrence of a recognition pulse for a spot on the side of the scanning raster must occur above the bottom of the vertical line segment indicated by the nonrecognition pulse symbol. This is indicated in Figure 12 by the dark spot 125, which must occur at the vside of the scanning raster prior to the end of the vertical line segment on the a" side of the scanning raster. As is indicated in Figure ll, a b pulse and a recognition pulse R6 are coupled to the input and circuit 56 of the memory stage M1 along with the output of the priming stage P6 derived from the output leads 70e. This introduces the condition that recognition must occur in the b side of the scanning raster after the occurrence of the end of the vertical line segment indicated by spots 121-1-23, this last condition being indicated by the dark spot 126.

When this recognition shape 120 is superimposed over the number 1 in the font of type illustrated in Figure 12, the priming tube P6 will not fire since no recognition will occur on the "b side of the scanning raster for the spots 125 and 126. Recognition for all spots will occur, however, for the numerals 6 and 7, as illustrated in Figure l2, thus eifecting iiring of the memory stage M1. The relay 86, bearing the Roman numeral I, is connected to the terminal 77 of the memory stage M1, so that this relay is energized by tiring of the memory stage M1, attracting the contact arm of relay 86 away from the terminal 97. This completes the routing circuit through A 15 Y Y Ythe contact arm of relay 89 to the upper contact arm of relay 90 associated with terminals 102 and 103 associated with the numerals 6 and 7 when the output device actuating voltage is applied to the terminal 116 upon ring of the stage 114 during the end-of-character reference.

In a similar manner, firing of the shape memory tube M2 is effected by ring of the priming stage P6, the reception of a recognition pulse from the n side of the scanning raster below the end of the vertical line segment, indicated by the symbols a and R0, and the reception of a recognition pulse from the b side of the scanning raster which occurred one pulse interval immediately preceding the occurrence of the lower spot on the a side. This latter pulse is designated R 1 and is obtained from the output of the clipped amplifier 83 of the pulse shift register 80. This produces recognition of the shape illustrated in column 112 beside the symbol M2.

The other shapes illustrated in column 112 of the program chart of Figure 10 produce tiring of the corresponding priming and shape memory stages by simultaneous voltages produced from the sources indicated in columns 107 to 110.

The program illustrated in Figure l and described above applies to one of the conventional fonts of type, sample letters of which are illustrated in Figure l2. More complicated programs can and have been devised which are applicable simultaneously to several fonts of type. This is accomplished by programming the unit to interpret characters to be read on the basis of common distinctive characteristics of each characterof the several diierent fonts of type. Where characters are fundamentally diferent in two type fonts, such as an open or a closed digit 4, more than one exit from the relay network (or equivalent) are often commoned to the same output terminal representing the given character. Experience has shown that one program handling several different styles and sizes of type simultaneously may require only a slight increase in equipment relative to that required for a single type font. Even hand printed characters made with reasonable care but without mechanical aids have been successfully identified by such programs without further refinements.

It will be observed that by reason off the programming of the above described system, instead of detecting particular shapes at xed positions on the raster, misalignment of characters to be read relative to the raster will not disturb the operation of the device providing only that the scanning area is adequate in size. The various shapes and patterns to be detected `are determined by counts or measurements from the first portions of these shapes encountered, thus effecting detection if the pattern is present irrespective of where it is located vertically on the scanning raster. To correct for greater misalignment, :gating circuits for changing the direct current on the vertical deection plates of the cathode ray tube may be provided which are activated on detection of various strokes approaching or reaching the very extreme limits of the scanning raster.

It may be seen that it is possible to recognize more complicated shapes than that described above for M2 solely through the use of the shift register by plugging the appropriate stages of the shift register into the input Wand circuit of a shape memory tube. In fact, it is possible to recognize whole characters by this means alone. Such a system would, obviously, require a pulse shift register or the logical equivalent delay line of sufficient length to correspond in time substantially to the period of scanning of the whole character to which the recognition and non-recognition signals are fed with the appropriate stages of the shift register or delay line tapped to make available at each of the delay stages the recognition and non-recognition signals delayed by the successive delay stages thereof. The recognition and non-recognition signals, occurring at any selected combinations of delay stages, may be fed to input And circuits of shape memory tubes or the like for simultaneous comparison or detection of patterns of recognition and/or non-recognition signals sensed at various points during the scanning of the `whole character to `provide a basis for character recognition. However a program utilizing two slits such as described abo-ve is often not the most appropriate for such a case. This type of program retains the feature of permitting recognition without regard to alignment as long as the character does not extend beyond the scanning limits. However, this type of program does not readily permit variations such as described above and therefore is primarily useful only where a single style and size of type is to be recognized.

While but one preferred embodiment of the invention has been specifically shown and described, various modiiications may be made therein 'without departing from the spirit and scope of the invention, and it is desired, therefore, that only such limitations shall be placed on the invention as are imposed by the prior art and are set forth in the appended claims.

What I claim is:

l. Apparatus for reading intelligence-bearing items comprising means for scanning the area of an item to be read in successive lines of scanning, means for sensing intercepts of any portions of the item with the incremental zones comprising each scanning line and producing recognition and nonreco-gnition signals, respectively, upon occurrence or absence of said intercepts, a plurality of time delay stages for delaying said recognition and nonrecognition signals for successive time intervals, means responive to designated patterns of recognition and nonrecognition signals occurring in preselected intrapattern time relation at selected delay stages wherever the patterns may occur along the scanning lines for recognizing shapes to be identified corresponding to said patterns, and means to provide an output signal indicative of the shape recognized.

2. Apparatus `for reading intelligence-bearing items comprising means for scanning an item to be read along a plurality of scanning lines, means sensing the item at a plurality of uniformly spaced sampling spots on each scanning line, said sampling spots occurring at a constant repetition rate and being arranged in two vertical columns located respectively to the left and to the right of the center of the scanning field, means responsive to the presence and absence of a portion of the item to be read occurring at said sampling spots for producing recognition and nonrecognition signals in accordance with the conditions sensed, analyzing means for analyzing the recognition and nonrecognition signals having means for detecting preselected signal conditions including preselected patterns of recognition and nonrecognition signals for successive sampling spots on single scanning lines, preselected pattern of recognition and nonrecognition signals for vertically aligned sampling spots, and preselected patterns of recognition and non-recognition signals for selectively related sampling spots in a plurality of said scanning lines, storage means for recording for the duration of the scanning of the item being read the detection of said preselected signal conditions, means for detecting the end of a character being scanned, and signal generating means conditioned by said storage means during scanning of the item in response to the accumulated recorded conditions therein to provide an output device actuating signal indicative of the item read, following detection of the end of the item.

3. Apparatus for reading intelligence-bearing items during continuous movement thereof comprising means `for scanning an item to be read along a plurality of scanning lines extending substantially parallel to the 'direction of travel of the items, means sensing the item at a plurality of spaced sampling spots on each scanning line, said spots being located uniformly along said scanningr lines to form vertical columns of sampling spots perpendicular to the direction of travel osaid items, means responsive to the presence and'absence of a portion of the item to be read occurring at said sampling sports for producing recognition` andY nonrecognition signals in accordance with the conditions sensed, counting means for producing signalsl on recurrence of ,successive recognition and nonrecognition signals'in selected vertical columns of said samplingspots, means frdelaying said recognition and nonrecognition signals for integral multiples of the period ofy said sampling spots, storage means for recording occurrence orf selected signal conditions for the duration of the scanning of tlie item being read, analyzing means responsive to simultaneous occurrence of selected recognition and nonrecognition signals, delayed recognition and nonrecognition signals, counting means signals to energize said storage means upon occurrence of selected sequences and recurrences of said recognition and nonrecognition signals, and signal generating means conditioned by said storage means during scanning of the item in response to` the accumulated recorded conditions therein to provide an output device actuating signal indicative ofthe item read.`

4. Apparatus for reading intelligence-bearing items during continuous movement thereof comprising means for scanning a plurality of times the area of each item to be read in scanning lines extending substantially parallel to the direction of travelof the items and progressing downward perpendicularly to the direction of travel of the items, means for sensing the occurrence and absence of portions of the item intercepting any one of at least'a pair of spaced sampling spots located uniformly along each scanning line, the sampling spots of the plurality of scanning linesbeing located in two vertical columns symmetrically spacedat opposite sides of the center of the scanning field, means for producing'recognition and nonrecognition signals in accordance with the condition-s sensed by the sensing means' at the sampling spots, analyzing means including a plurality of comparator circuits and counter circuits for sensing the occurrence of preselected sequences and recurrences of said recognition and nonrecognition signals, storage means for recording for the duration of Yone scanning cycle the sensing of certain sequences and recurrences of recognition and nonrecognit'ion signals by said analyzing means, other storage means for recording for the duration of the scanning of an item being read certain recordings by the ilrst mentioned storage means together with sensing of selected sequences and recurrences oi said recognition and nonrecognition signals by said'analyzing means, and'signalgenerating means producing an output device actuating signal immediately following complete scanning of an item and conditioned by said storage means in response to the accumulated recorded conditions therein to provide an output signal indicative of the item read.

5. Apparatus for reading intelligence-bearing characters comprising scanning means for progressively scanning a scanning eldand producing` scan signals characteristic of characters scanned therein, and interpreter means responsive to selected intracharacter relationships of portions of the characteristic scan signals of a character includingmeans to render the interpreter means free of dependence upon any selected reference relationship ofl the characters with'the scanning field whereby the interpreter means can identify the selected intracharacter relationships regardless of where the character may occur in the scanning iield for producingV output signals indicative of the character scanned.

6. Apparatus for reading'intelligence-bearing characters comprising scanning means'for progressively-scanning a scanningiield,y detector means for' generating a scan signal for each character scanned in said held having a wave shape characteristic of the character scanned, scan signal interpreter means responsive to selected ypatterns of wave shape portions identifying the characters scanned in said scan signals for interpreting the patterns and recognizing the characters tl icrefrom including means for producing a datum signalfin responser to selected character detectionevents providingv a reference' datum for locating selected patterns in said -wave shape' relative to the character scannedfand'meansfor detectingselected patterns in said Wave shape in'preselectedreference relationship with the scharacter scanned responsive to the time relationship between portions of the patterns and said datum signal'to detect selectedintracharacter relationships denoted by said patterns regardless of Where the characters occur in the'scanning eldfto sense the `identity of' the character therefromv and produce output signals indicative of the character scanned.

7. The combination recitedin claim 5,y including Ameans to sample different portions ofy the scan'signal for each character, and means to convert the samples from each scan signal derived from a'cliaracter' to a code number representative of said lcharacter.

8. The combination-recited'in claim` 5 wherein said interpreter' means includes aiplinality` of delay-y means responsive to sean signals applied theretowfor producing delayed output signals substantially identical'to said scan signal but delayed byY preselected time intervals, and means forf sen-singl signals applied to said delay means ata' plurality of sampling points separated by preselected timedelay intervals for simultaneously sensing av plurality` of portions oflsaid'scan signal generated'at dilerent times during scanning of acharacter.

9. Apparatus'fn'or reading intelligence-,bearing vcharacters comprising scanning means `for scanningthe characters successively along a plurality ofrectilinear scan lines, detector= means for sensing interception of thesoan line by the character during a/-lin'e'fscan andiproducing intercept and non-intercept scan signals respectively denoting interception and non-interception ofthescan line by ,a portion' of the character', scansignal analyzer means responsive to patterns-ofsaid intercept and? non-intercept scan signals having preselected intra-character relationships-for recognizing the patternsincluding means to render the interpreter means free of dependence upon the location of the character? alongthe axis of the scan line comprising means for sensing the time relationship lwithin the scan |line of the seansign'als' relative to a selected interceptI scan signal offthatI scan line anddetecting therefrom'4 patterns of interceptl and? non-intercept scanv signals denoting characteristics which differentiate between characters whereby the interpreter means-can identify thepatterns independent of'fthe location of the clianacte'rialong` the axis ofthe `sean-line, and'outputsignal generating meanslre's'ponsive to preselected combinations of p'atternsdetectedj by said analyzer means for producing output signals indicative of` the character scanned.

10. Apparatus for reading intelligence-bearing chanacters comprising scanning means for scanning the characters successively .along -a plunalityof'rectilinear scanlines, detector means for sensing interception of each' scan line by the character during the line sean andproducing intercept' and non-intercept scan-signals respectively' denoting interception and non-interception of the scan line by a portion of the character, scanl signal analyzer mean'sresponsiveto patterns ofsaid intercept and non-intercept scan' signals having preselected intra-character relation'- ships for identifying combinations of'selectedidentication factors of the characters including means `for producing a datum signal in response to a4 selectedscan signal pattern providing a referenceV datum for locating the patterns of intercept-and non-intercept scan-signals produced' inf'said line scanrelative tothe character scanned and means for detecting selected patterns-ofv said intercept and non-intercept" scan* signals in preselectedI reference relationshipwith the character scanned responsive-to the time relationship between-the intercept and non-intercept i9 signals comprising the patterns and said datum signal to detect character identification factors denotedwby the reference patterns and generate a signal indicative of the factor detected, and output signal generating means responsive to preselected combinations of identification factors detected during the scanning of a whole character for producing output signals indicative of the character scanned.

l1. Apparatus for reading intelligence-bearing characters comprising scanning means for scanning each character in a plurality of successive scanning frames progressing laterally across the character, each scanning frame comprising a plurality of laterally spaced rectilinear scan lines extending vertically of the character in parallelism with each other and having a length greater than the height of the characters, detector means for sensing interception of each yof the scan lines comprising a scanning frame by the character during a frame scan and producing intercept and non-intercept scan signals respectively denoting interception and non-interception of the scan line by a por-tion of the character, scan signal analyzer means responsive to patterns of said intercept and non-intercept scan signals having preselected intracharacter relationships for recognizing the patterns including means for sensing the time relationship within the scanning frame of the scan signals relative to a selected intercept scan signal in that scanning frame and detecting therefrom patterns of intercept land non-intercept scan signals denoting characteristics which differentiate between characters independent of the vlocation of the characters along the scan lines, and output signal generating means responsive to preselected combinations of patterns detected 'by said analyzer means for producing output signals indicative of the character scanned.

12. Apparatus -for reading intelligence-bearing characters comprising a scanning station, means for establishing a scanning frame for inspection of characters progressing laterally through said station wherein a plurality of such scanning frames successively traverse the characters, said scanning frame comprising -at least a pair of rectilinear scan lines spaced apart a fraction of a character space and extending vertically of the character and traversing a length greater than the height of the character, detector means for sensing interception of the scan lines by the character during a scanning frame and producing intercept and non-intercept scan signals respectively denoting interception and non-interception of the scan line by a portion of Vthe character, interpreter means responsive 'to selected patterns of said intercept and nonintercept scan signals denoting preselected intracharacter identification factors including means to render the interpreter means free of dependence upon the location `of the character along the aXis of the scan lines for detecting from said patterns identification `factors which differenti- -ate between characters whereby the interpreter means can identify said identiiica-tion factors independent of any preselected registry relationship of the characters with the scanning frame and means responsive to preselected combinations of the identification factors detected for producing output signals indicative of the `char-acter scanned.

13. Apparatus for reading intelligencebearing characters comprising scanning means for; scanning a character bearing area in rectilinear scanning lines defining a scanning field and producing scan signals indicative of interception and non-interception of said scanning lines with a character scanned, and scan signal interpreter means responsive to selected patterns of intercept and nonintercept denoting scan signals signifying preselected intracharacter relationships wherever said patterns may occur in lthe scanning field lfor ldetecting characteristics which differentiate between characters and producing signals responsivey to preselected combinations of differentiating characteristics detected indicative of the character scanned, said interpreter means including a plurality of delay means responsive to input signals applied thereto for producing delayed output signals substantially identical to said input signals but de layed by a preselectedrtime interval, a plurality of settable means disposed to assume a set condition in response to set signals applied thereto and to resume a reset condition in response -to reset signals applied thereto and producing condition-indicating output signals, a plurality of coincidence detecting means responsive to at least two input signals applied thereto for producing `output signals only during time coincidence `of said input signals, a plurality of measuring means responsive to the extent of yan input signal sequence applied thereto for producing an output signal indicative of the extent measured, and a plurality of connecting means for connecting said scanning means, said delay means, said settable means, said coincidence detecting means and said measuring means, by conductively bridging selected pairs of output and input terminals thereof in a plurality of combinations appropriate to effect a selected program for said interpreter means.

14. Apparatus for reading intelligence-bearing characters comprising scanning means for scanning a character bearing area in rectilinear scanning lines defining a scanning field and producing scan signals indicative of interception and non-interception of said scanning lines with a character scanned, and scan signal interpreter means responsive to selected patterns of intercept non-intercept denoting scan signals signifying preselected intracharacter relationships wherever said patterns may occur in the scanning field for detecting characteristics which differentiate bet-Ween `characters and producing signals responsive to preselected combinations of differentiating characteristics detected indicative of the character scanned, said interpreter means including a plurality of settable lmeans disposed to assume a set condition in respouse to set signals applied thereto 'and to resume a reset condition in response to reset signals applied thereto and producing condition-indicating output signals, a plurality' of coincidence detecting means responsive to at least two input signals applied thereto for producing output signalsonly during time coincidence of said input signals,l a plu-v rality of measuring means responsive to the exten-t of anl input signal sequence applied thereto for producing arr output signal indicative of the extent measured, and a plurality of connecting means for connecting said scarA ning means, said settable means, said coincidence detectJ ing means and said measuring means, by conductiveiy bridging selected pairs `of output and input terminals thereof in a plurality of combinations appropriate to effect a selected program for said interpreter means.

l5. Apparatus for reading intelligence-bearing characters on la character-bearing surface during continuous movement of the characters comprising means for progressively optically superimposing over new areas of a character to be read a scanning raster including means Lfor sweeping a beam of energy in successive scanning lines substantially paralleling the aXis of movement of the characters and progressing perpendicularly to said axis of movement and means for electronically gating said beam of energy to produce uniformly located spaced spots, of light along each scanning line in a manner providing Ia plurality of parallel columns of light spots arranged perpendicular to said axis `of character movement 'wherein said columns of light spots are spaced from each other tospan a lfraction of a character area, means including an element responsive to reflected light originating in said spots and reflected from said surface for detecting changcs in the amount of energy reflected from said surface and producing intercept and non-intercept scan signals respectively denoting presence and absence of portions of a character intercepting said spots of light in each column of spots, interpreter means responsive to patterns of said `intercept and non-intercept scan signals signifying selected intracharacter identification. factors including means to render the interpreter means free of dependence upon the location of the character along the axis of the scanning lines fwhereby the interpreter means can identify said patterns regardless of Where the patterns may occur along said columns of spots of light for detecting identitication factors denoted by said patterns which differenti-ate between characters :and producing in-terpreter signals indicative of the identiiication factors detected, and means responsive to preselected combinations of the identification factors detected for producing output signals indicative of the character scanned.

16. Automatic character sensing apparatus comprising a scanning station, means for progressing characters laterally through said scanning station `along a preselected axis of character progression, means for scanning each character progressively along a plurality of successive rectilinear scanning lines extending perpendicular to the axis Iof character progression having a length greater than the height of the characters and progressing laterally in parallelism fwith each other over the character area, means for sensing interception of the scanning lines by the character during a line scan and producing intercept and nonintcrcept scan signals respectively denoting interception and non-interception of the scan line by .a portion of the character, scan signal analyzer means -responsive to selected patterns of said intercept land non-intercept scan signals including means to render the interpreter means free of dependence upon the location of the character along the axis of the scanning 'lines whereby the interpreter means can identify said patterns regardless of where the patterns may occur along the scan lines for detecting from intracharacter relationships of the pattern portions selected factors of length, continuity, shape, and relative location of various portions ofthe character scanned, storage means for recording for, selected periods during the scanning cycle of a whole character the Ifactors detected by said analyzer means, and output signal generating means responsive to preselected combinations of factors detected by said analyzer means denoted by the accumulated recorded conditions in said storage means to provide output signals indicative of the character read.

17. Apparatus for reading intelligence-bearing characters comprising means for sensing the area of a character to be read in rectilinear sensing increments progressing in parallelism 'with each other over the character area defining a sensing field and producing sensing signals characteristic of the characters sensed, means for processing the sensing signals to produce processed signals representing selected functions of the sensing signals, a plurality of successive time delay stages to delay said processed signals for successive time intervals, means responsive to predesignated combinations of signals derived from said time delay stages regardless of where the character is located in the scanning field for recognizing selected shapes to be identified corresponding to said combinations of signals including means for sampling said time delay stages to detect at one point in time a plurality of delayed processed signals which where applied to said time delay stages at different points in time, and means to provide an output signal indicative of the shape recognized.

18. Interpreter means for automatic character sensing apparatus for analyzing electrical signals characteristic of the characters derived from sensing of the characters as they pass through a sensing station to analyze the signals derived from a character in selective timed relation to each other, said interpre-ter means including delay means comprising a plurality of delay stages arranged in succession with the inputs of each stage following the first stage coupled to the output of the preceding stage, means for applying said characteristic signals to the input of the first delay stage, each delay stage producing delayed output signals substantially identical to the input signals applied thereto but delayed by a preselected time interval relative to the corresponding input signals, and sampling means intercoupled with the delay stages of said delay means for sampling the signals applied to said delay means at a plurality of selected delay stages of said delay means to sample at one point in time a plurality of delayed signals therein which were applied to said delay means at different points in time for sensing said signals in time referenced relation to each other.

19. Scanning apparatus for automatic character sensing equipment for producing scan signals characteristic of the characters on a character-'bearing surface as the characters progress through a scanning station, com prising means for optically imaging onto characterbearing areas of the character-bearing surface within the scanning station a plurality of repetitive scanning patterns of light energy to be advanced in successive patterns laterally across the character-bearing area during advancement of the characters, each of said scanning patterns comprising at least a pair of laterally spaced scanning strokes extending vertically of the characters and spaced to span a fraction of the character width, said scanning strokes being of a length greater than the height of lthe characters, and the light energy being scanned from one end of the scanning strokes comprising a single scanning pattern to the other in laterally coordinated relation whereby the light energy progresses substantially simultaneously along the associated scan lines of a pattern, and means responsive to reiiected light originating in the scanning pattern and retlected from said surface for detecting changes in the amount of light energy reflected from the surface and producing intercept and non-intercept scan signals respectively denoting the presence and absence of portions of the character intercepting said scan strokes.

References Cited in the file of this patent UNITED STATES PATENTS 1,815,996 Weaver July 28, 1931 1,870,989 Eldred Aug. 9, 1932 2,039,406 Greensfelder May 5, 1936 2,370,160 Hansell Feb. 27, 1945 2,615,992 Flory Oct. 28, 1952 2,616,983 Zworkykin Nov. 4, 1952 2,624,798 Dinga Jan. 6, 1953 2,663,758 Shepard Dec. 22, 1953 

